New Mexico Geological Society Annual Spring Meeting — Abstracts

The Department of Energy funded a study of coal reserves in the San Juan Basin, New Mexico. From this study, the updated demonstrated reserve base (DRB) estimate is 11.24 billion short tons (st) of surface and deep coal. This compares with 4.429 billion st in the Energy Information Administration's ORB for all of New Mexico, and 2.806 billion st for the San Juan Basin, as of January 1, 1993. These new estimates of "remaining" coal resources include significant adjustments for past production and recovery rates (through 1994). The updated estimates also incorporate analyses of available sulfur, heat, and ash content data for characterizing New Mexico's remaining coal resources. Coal quality data were examined along with coal resource data. The preliminary remaining, surface minable DRB estimate for the Bisti field is 872.25 million st of subbituminous low-sulfur coal.

In 1996, the US Geological Survey funded a 1 Ω-year study to evaluate available resources in a four-quadrangle area in the northwest Bisti field. This study differs from the DRB because 1) it uses GIS for reserve calculation rather than hand calculations 2) the Fruitland Formation coals are broken down into zones for quality analyses and reserve calculations. More raw data was added to the existing database to accomplish the correlation of zones.

Using EI Paso Natural Gas Co.is designations, four zones were correlated in the Fruitland Formation, the Yellow, Blue, Green, and Red zones, in descending order. The average thickness of the coal-bearing Fruitland is 172 ft, when the Yellow zone is present. The Red zone, at the base of this unit has the most laterally consistent coals. All the zones have coal beds averaging 6 to 8 ft with maximum coal thickness of 20 to 30 ft. When the quality analyses were divided into zones and weighted by thickness of seam, all of the zones averaged medium sulfur content (Lbs Sulfur/Million Btu).